1. Technical Field
The invention relates to an externally visible 180 degree hinge for switching boxes, comprising a first bearing block attached to the box casing and a second bearing block which surrounds the first bearing block, is U-shaped, bolted to the door leaf or attached by means of clamping bolts, the second bearing block being pressed into a recess arranged at the edge area of the door leaf and thus surrounding the recess edges, the axis of rotation of the hinge being outside the corner formed by the edge of the door leaf.
2. Discussion of the Prior Art
A 180 degree hinge also by the applicant of the present hinge, which can be used for switch boxes in series, is known from catalogue sheet C085.4 of the company EMKA Beschlogteile GmbH & Co. KG, printed in Mar. 1986. This 180 degree hinge is suitable for salient doors and can be used both left and right, with a maximum opening angle of 180 degrees in applications in series boxes, so that extremely easy access is possible to the contents of the box as well as the components attached to the door leaf.
The known EMKA hinge has considerable advantages over earlier designs. One advantage exists in the fact that the welding process for attaching the second bearing block to the door leaf, or the use of fixing bolts for the door leaf (if this is envisaged as an alternative) can be omitted, whereas for attaching the first block either a cap screw or a screw bolt or even a stay bolt (welding bolt) can be used.
A similar U-shaped block held in a door leaf by means of a recess is shown in FIG. 7 of European patent application 85114300.8.
However, in order to remove the door with the known 180 degree hinge arrangements with clamping pin devices in order to obtain better access to the interior of the box for wiring, for example, a considerable amount of work is necessary. Either the screw connections between box casings and the several hinges of each door have to be unscrewed, or the bolts of the clamping device for the various hinges have to be removed, which then causes the hinges to fall apart. Subsequent reassembly is difficult, particularly if three hinges have to be assembled at the same time and because of the necessary precise orientation of the individual hinge components.
An even more serious disadvantage is that the older state of the art can only be applied in the case of individual boxes, not series boxes.
Hinges for a door with a 180 degree opening angle which can also be used for series boxes, are disclosed in DE-OS 32 46 398 by the applicant. The series box hinge arrangement proposed in this publication requires space next to the door leaf corresponding to the basic width of both hinge blocks. For this reason when a 180 degree hinge of this type is used for series boxes the door leaf has to be narrower than the box casing by a little more than the basic width of the hinge, for aesthetic reasons this gap also provided at the top and bottom of the door leaf. This hinge also requires asymmetrical fixing borings, so that a prepared, i.e. holed, door leaf cannot be used for both left and right unless additional borings are provided. It would be more advantageous if, in a 180 degree hinge, the door leaf essentially covers the surface of the box casing so that only a narrow edge of 1 to 3 mm, for example, remains for taking up manufacturing tolerances. The 180 degree hinge known from the aforementioned catalogue sheet permits this surface covering door leaf size and can still be used in series boxes. In addition, if necessary, fixing to the door leaf can be implemented without screw holes. It is also possible to interchange hinge types (e.g. replacing a 180 degree hinge for individual boxes, as illustrated in catalogue sheet C085.2 for example, by a 180 degree hinge for series boxes in accordance with catalogue sheet C085.4), without modifications having to be made to the door leaf or box casing, with the possibility of use on both left and right remaining.